1. Field of the Invention
The present invention relates to novel azo dye compounds, inks separately containing such azo dye compounds as a recording agent, and an ink-jet recording method and an instrument using such an ink. More particularly, this invention relates to novel azo dye compounds suitable for use in the preparation of inks which can provide images high in optical density, scarcely cause feathering of dots and permit fast fixing and improved water fastness when printed on so-called plain paper such as woodfree paper, paper for copying, bond paper and paper for reporting, inks separately containing such dye compounds, and an ink-jet recording method and an instrument using such an ink.
2. Related Background Art
Water-based inks with a water-soluble dye dissolved in an aqueous medium have heretofore been used as inks for ink-jet recording. Such conventional inks are required to satisfy the following conditions:
(1) providing images sufficient in optical density; PA1 (2) having good drying characteristics on a recording material; PA1 (3) providing recorded images on which feathering scarcely occurs; PA1 (4) providing recorded images free from running even when coming into contact with water, alcohol, etc., or sufficiently readable even when run out (high water fastness); PA1 (5) providing recorded images excellent in light fastness: PA1 (6) causing no clogging on the tip of a pen or nozzle; PA1 (7) having no defects such as blurring of recorded images upon continuous recording or resumption of recording after being over for a long period of time (good ejection stability); PA1 (8) being able to store stably; PA1 (9) offering no problem even when coming into contact with parts constructing a recording means during use; and PA1 (10) offering no problem about the safety of users. In addition, in an ink-jet recording system making use of thermal energy, the inks are required to satisfy the following conditions: PA1 (11) having excellent heat resistance and not adversely affecting a means for generating thermal energy. PA1 Group A: H, OH, NH.sub.2, CN, .dbd.O and the second amino acid residue; PA1 Group BB: H, OH, NH.sub.2, CN and .dbd.O, PA1 Group A: H, OH, NH.sub.2, CN, .dbd.O and the second amino acid residue; PA1 Group BB: H, OH, NH.sub.2, CN and .dbd.O, PA1 Group FF: H, OH, NH.sub.2, CN, .dbd.O and --N(H).sub.n (CH.sub.2 CH.sub.2 OH).sub.2-n, in which n is a number of 0 or 1; PA1 Group G: H, OH, NH.sub.2, CN and .dbd.O. PA1 Group FF: H, OH, NH.sub.2, CN, .dbd.O and --N(H).sub.n (CH.sub.2 CH.sub.2 0H).sub.2-n, in which n is a number of 0 or 1; PA1 Group G: H, OH, NH.sub.2 , CN and .dbd.O. PA1 Group J: H, OH, NH.sub.2, CN, .dbd.O and --N(H).sub.n (CH.sub.2 CH.sub.2 OH).sub.2-n, in which n is a number of 0 or 1; PA1 Group KK: H, OH, NH.sub.2, CN and .dbd.O. PA1 Group J: H, OH, NH.sub.2, CN, .dbd.O and --N(H).sub.n (CH.sub.2 CH.sub.2 OH).sub.2-n, in which n is a number of 0 or 1; PA1 Group KK: H, OH, NH.sub.2, CN and .dbd.O.
These properties or characteristics may of course vary according to the composition of ink, and also are greatly controlled by the nature of a dye contained as a recording agent. It is difficult to satisfy all the above requirements for performance by using existing dyes.
The conventional water-based inks for ink-jet recording have used principally existing acid or direct dyes. These dyes each have a sulfonic group as a solubilizing group, and hence are high in solubility in media for water-based inks, and hence, the long-term storability of inks containing such a dye is generally good. However, a print obtained by making a record with such an ink on a recording material such as paper or the like has undergone running of the dye and bleeding when it was splashed with water or touched with a wet finger, or characters on the print were rubbed with a water-based felt pen, so that the print has often been deteriorated in image quality and made illegible.
Japanese Patent Application Laid-Open Nos. 55-145773, 59-78273, 59-131657, 60-81266, 60-188468, 61-2773, 61-2774, 61-247770, 61-62562 and 63-213582, and moreover Japanese Patent Application Laid-Open Nos. 58-101171, 58-141257, 59-64677, 1-141966 and 4-52305 separately disclose inks the various properties of which have been improved by using a monoazo dye having a specified structure. However, the water fastness of recorded images formed with such inks is still insufficient.
Japanese Patent Application Laid-Open Nos. 55-151072, 59-100164, 61-2776, 61-57666, 61-261377, 3-39372 and 3-1576 separately disclose inks the various properties of which have been improved by using a disazo dye having a specified structure. However, the water fastness of recorded images formed with such inks is still insufficient.
Japanese Patent Application Laid-Open Nos. 54-154605, 59-75966, 61-171780, 61-225267, 61-285276, 62-50371, 62-201978, 63-137975, 63-289079, 64-48873, 64-54082, 1-165678, 1-210464, 3-167270, 3-200882, 4-108865, 4-175384, 4-202571 and 4-202573, and Japanese Patent Application Nos. 2-30662, 2-30663, 2-415359, 2-408933, 2-408934 and 3-16824 separately disclose inks the various properties of which have been improved by using a trisazo dye having a specified structure. However, the water fastness of recorded images formed with such inks is still insufficient.
Japanese Patent Application Laid-Open No. 57-59969 discloses a water-based ink using, as a colorant, an alkali metal salt of an amide derivative obtained by reacting an acid group of an acid dye with an aminocarboxylic acid. However, the process of such a reaction is complex and difficult, and so the production cost of the colorant becomes expensive. In order to well balance the solubility of the dye with the water fastness of the ink, it is also necessary to control the proportion of the number of sulfonic groups to the number of carboxyl groups in a molecule of the dye. It is however next to impossible for this process to provide such control. Japanese Patent Application Laid-Open No. 1-141966 discloses a water-based ink containing a dye in which a ratio of a carboxylate group to a sulfonate group in its molecule is 0.3 or higher, and these groups form salts with a quaternary ammonium or lithium. As apparent from the specific examples, the carboxyl group in this dye is bonded directly to an aromatic ring in its molecule. Besides, Japanese Patent Application Laid-Open No. 61-43673 discloses an ink containing a monoazo dye in which a carboxyl group is bonded directly to an aromatic ring. However, the use of these particular intermediates inevitably brings on a considerable increase in cost. In addition, such inks can stand improvement in the water fastness of images formed with the inks.
Japanese Patent Application Laid-Open No. 60-81265 discloses an ink-jet ink making use of a disazo dye having a carboxyl group. In this dye, 3 or 4 sulfonic groups are also introduced. Japanese Patent Application Laid-Open No. 3-91577 discloses an ink-jet ink making use of a disazo dye in which 2 carboxyl groups and 1 or 2 sulfonic groups are introduced to aromatic rings.
Japanese Patent Application Laid-Open No. 4-220472 and Japanese patent Application No. 3-16825 separately disclose a trisazo dye, in which 2 or more carboxyl groups are introduced into its molecule.
As described above, various devices have been made for improving various properties such as water fastness at the same time. The problems have not yet been solved in a satisfactory manner. Besides, there is a demand for development of an ink which can form dots free from feathering, substantially round in shape and sharp in edge and hence provide images high in quality, and an ink which permits fast fixing after recording for accommodating the speed-up of printers.
When during printing of a document or image having blank spaces, printing is suspended on nozzles corresponding to the blank spaces, the direction of the first ejection upon resumption of the printing tends to disorder, resulting in a print deteriorated in quality. Therefore, there is also a demand for development of an ink free from such a problem.